That's a lot of dust!!!!
I use a air compressor, but i make sure its completely drained of any water inside and not blowing out condensation before using it. then i let the PC sit for a while before hooking it back up to power just to be safe no moisture got into anything.
Also with 150psi of air pressure its very wise not to allow any fans at all to free spin with that amount of air force, it can easily kill a fan, i know 1st hand...like a fool back in 2003 i killed a ati 9700 or 9800pro fan by letting it free spin to probably 15000+ rpms, it made a awesome zipping noise and cleaned it very well but. Needless to say it never worked again.
Now whenever i blow out my fans i use a qtip or toothpick to keep the fan from free spinning above a hundred rpms or so.
With having 2 large great danes and me and the wife smoking i have to clean them about once every 2-3 months.
Having a coolermaster HAF922 is second to none keeping my components cool with very minimal noise with the 2x200mm fans 1 front and one side intake, 2x 120mm orange silent fans on the radiator and 1 bottom 120mm intake and 2 top exhaust 120mm fans all hooked up to NZXT senrty fan controller everything stays very cool but very quiet. But with all that airflow they should have named it the dustmaster since they only included a front dust filter that is a PITA to get to. But with all that airflow its a virtual air purifier
I only use the vacuum with the brush on my h60 radiator....never on a circuit board with the air rushing by the bristles you are bound to build up a decent electrical charge just from the air being pulled by the brush, so using it on a board of any type you are asking for trouble.